ABSTRACT The CATALyST (Consortium for Applied Training to Advance the Learning health system with Scholars/Trainees) Center of Excellence will support a new generation of learning health system (LHS) researchers. We will recruit and train 8 multidisciplinary scientists for careers in translational research partnering with LHSs focused on improving patient-centered outcomes, healthcare quality, safety and equity. Our clear theoretical underpinning of LHS competencies, woven throughout the training program, is built on the long history of Kaiser Permanente Washington, University of Washington and the VA Puget Sound Health Care System as LHSs, with new LHS partner Washington State University College of Medicine. Our established relationships with operations partners in our healthcare systems with diverse populations, services, and care models, are the foundation of our K12 program and will enable scholars to succeed as the future leaders of LHS research. Our long-term goal is to produce independent scientists with a solid foundation in LHS research and rapid implementation of evidence that will improve healthcare quality and patient outcomes and experience. CATALyST will achieve this goal through recruiting and training highly qualified early career investigators, and training them in cutting-edge methods of LHS science and patient centered outcomes methodology. Our curriculum will be informed by our long history of translational LHS research, and our diverse scholars will be embedded in rich LHS environments with varied faculty and many opportunities to engage directly in ongoing and new LHS studies. Diana Buist, PhD, MPH and Paula Lozano, MD, MPH will serve as Multiple PIs. These leaders combine expertise in LHS research, experience in mentorship, and demonstrated collaboration across our regional partners. Our overall aims are to: 1. Establish a LHS Research Training Center of Excellence, participate in AHRQ's national LHS learning collaborative, and support cross-institutional LHS training, networking, research and dissemination. 2. Identify, recruit and provide LHS scholars with multidisciplinary didactic and experiential training in: a. Using core LHS competencies that incorporate patient-centered outcomes research and methods, implementation science, adaptive/pragmatic design, and informatics. b. Engaging patients and other stakeholders (e.g., healthcare executives, operational and clinical leaders) from research inception to completion to implementation. c. Designing and conducting studies in LHS systems to generate, adopt, and apply evidence to improve healthcare quality, safety and equality. 3. Engage scholars in the existing and new LHS research opportunities provided by our collaborations, data infrastructure, and established relationships with delivery systems and patient stakeholders at our partnered LHS organizations.